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M1.7 earthquake 6 km N of Healdsburg, California, United States

A magnitude 1.7 earthquake struck 6 km N of Healdsburg, California, United States at 01:30 local time (08:30 UTC) on 24 Sept 2026, at a depth of 6 km, according to USGS. The solution is preliminary and may be revised.

Data: USGS · updated 2026-09-24 09:07 UTC · automatic solution

Magnitude
1.7micro
duration magnitude (md)
Depth
6.2 km
Status
Automatic
Origin time
2026-09-24 08:30:11 UTC
Local: 24 Sept 2026, 01:30:11 (America/Los Angeles)
Epicentre
38.659° N, 122.881° W

Circles show this event and others within 30 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map

Nearby places

Distance and estimated shaking at nearby places
PlaceDistanceEst. shaking
HealdsburgCalifornia, United States · pop. 11,7426 kmIIWeak
WindsorCalifornia, United States · pop. 27,46413 kmINot felt
Santa RosaCalifornia, United States · pop. 178,12729 kmINot felt
Rohnert ParkCalifornia, United States · pop. 42,40739 kmINot felt
Agua CalienteCalifornia, United States · pop. 27,09051 kmINot felt
San FranciscoCalifornia, United States · pop. 827,526107 kmINot felt
OaklandCalifornia, United States · pop. 419,267109 kmINot felt
SacramentoCalifornia, United States · pop. 524,943121 kmINot felt

Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more.

Every agency's solution

Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS · NC.

AgencyMagnitudeDepthEpicentreTime offsetStatus
USGS · NCheadlineNorthern California Seismic System via U.S. Geological Survey1.7 md6.2 km38.66° N, 122.88° W–Automatic

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How big was it?

Usually not felt. Recorded by nearby seismometers; thousands occur worldwide every day.

It released roughly the energy of 6 kg of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 6 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.

M1.7 releases about 13× the energy of M1.0, and its waves are about 5.5× taller on a seismogram. Energy: 6 kg of TNT vs 477 g of TNT.

Each square is the energy of one M1.0. Energy from log₁₀E = 1.5M + 4.8.

Aftershocks and nearby activity

171 later earthquakes within 30 km; the largest was M2.1 1 day ago. 59 in the 7 days before. Aftershock rates usually fall off roughly in proportion to 1/time.

Aftershocks

Mainshock M1.7

171 later earthquakes nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).

Aftershocks
Time after mainshock (hours)MagnitudeDepth (km)
0.660.615
1.770.81
3.350.71
3.881.13
3.891.13
3.951.31
4.150.72
4.731.7-1
5.411.42
5.521.32
6.770.62
7.420.83
7.831.03
9.050.32
9.821.02
10.050.72
12.440.83
12.441.63
13.540.93
15.100.21
16.901.03
17.040.62
17.050.72
17.931.02
18.081.02
18.191.03
18.600.43
18.921.11
18.930.81
19.050.82
19.620.73
20.090.82
20.180.72
20.451.12
21.601.51
23.131.33
23.920.32
25.900.72
26.661.015
27.690.82
27.750.72
28.481.03
29.120.72
29.620.61
31.160.43
33.130.62
33.290.62
33.610.72
34.021.03
35.450.82
35.521.12
35.801.22
35.831.33
36.570.72
37.091.33
37.101.63
37.831.33
38.160.32
39.040.73
39.281.43
39.990.73
40.990.72
41.751.22
42.050.72
42.561.32
42.850.82
43.310.85
44.080.33
44.971.10
45.570.62
45.740.83
46.450.33
46.470.92
46.571.12
46.651.3-1
48.001.12
48.060.83
48.311.52
50.870.82
51.270.76
51.351.13
53.311.01
53.421.12
53.561.02
56.270.81
56.301.30
56.591.92
57.640.72
57.780.22
58.011.52
58.300.82
60.810.33
61.481.32
63.241.12
64.941.11
66.101.14
67.811.13
68.170.71
68.921.31
68.920.61
68.950.32
69.081.01
69.371.13
69.681.22
70.090.71
70.240.72
70.501.31
71.170.53
71.440.62
72.072.02
72.071.52
72.090.32
73.960.81
74.110.72
74.120.72
74.201.12
74.470.72
74.580.71
74.821.12
75.290.62
75.310.32
76.061.32
76.740.83
79.611.33
79.820.83
80.420.93
83.191.12
83.210.71
83.262.13
83.291.23
83.521.13
83.591.42
84.551.22
84.871.52
85.170.33
85.240.82
86.601.10
87.750.84
91.330.73
91.370.82
92.011.25
92.031.86
92.610.31
93.311.52
93.710.82
94.000.82
94.311.02
95.451.33
96.190.916
96.401.45
96.921.52
97.690.82
98.190.34
98.290.83
98.810.82
100.020.83
101.040.83
103.310.71
103.820.72
103.830.72
104.131.63
105.440.82
105.761.12
106.110.51
106.490.62
107.842.11
107.860.61
107.860.80
107.860.80
107.941.40
108.740.73
  1. 2.118 km E of Cloverdale, California, United States09-27 19:45
  2. 2.116 km ENE of Cloverdale, California, United States09-28 20:20
  3. 2.019 km E of Cloverdale, California, United States09-27 08:34
  4. 1.919 km E of Cloverdale, California, United States09-26 17:05
  5. 1.810 km ESE of Cloverdale, California, United States09-28 04:31
  6. 1.715 km E of Cloverdale, California, United States09-24 13:14
  7. 1.618 km E of Cloverdale, California, United States09-24 20:56
  8. 1.619 km W of Hidden Valley Lake, California, United States09-25 21:36
  9. 1.620 km E of Cloverdale, California, United States09-28 16:37
  10. 1.519 km E of Cloverdale, California, United States09-27 08:34
  11. 1.520 km W of Hidden Valley Lake, California, United States09-25 06:06
  12. 1.513 km E of Cloverdale, California, United States09-26 08:48
  13. 1.518 km W of Hidden Valley Lake, California, United States09-28 05:48
  14. 1.515 km E of Cloverdale, California, United States09-28 09:25
  15. 1.513 km WSW of Hidden Valley Lake, California, United States09-26 18:30
  16. 1.518 km E of Cloverdale, California, United States09-27 21:22
  17. 1.416 km N of Healdsburg, California, United States09-28 08:53
  18. 1.416 km ENE of Cloverdale, California, United States09-28 20:26
  19. 1.418 km E of Cloverdale, California, United States09-25 23:46
  20. 1.418 km E of Cloverdale, California, United States09-24 13:54
  21. 1.418 km W of Hidden Valley Lake, California, United States09-27 20:05
  22. 1.319 km W of Hidden Valley Lake, California, United States09-25 20:20
  23. 1.318 km W of Hidden Valley Lake, California, United States09-26 21:58
  24. 1.319 km E of Cloverdale, California, United States09-27 16:06
  25. 1.318 km E of Cloverdale, California, United States09-24 12:26

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Reports on SeismoAtlas

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Event id nc75440767. First recorded here 28 Sept 2026, 17:32:10 UTC. Solutions: USGS · NC (usgs:nc75440767). Cite as: SeismoAtlas, “M1.7 earthquake 6 km N of Healdsburg, California, United States”, https://seismoatlas.com/earthquake/nc75440767-m1-7-earthquake-6-km-n-of-healdsburg-california-united-states, data from USGS.

JSON: /api/v1/events/nc75440767. SeismoAtlas is not an official warning service.